The present invention relates to a heavy duty pneumatic radial tire having a block-based tread pattern, and more particularly to a heavy duty pneumatic radial tire adapted to suppress an occurrence of heel-and-toe wear without substantially reducing a tire performance such as a wet traction performance and a drainage performance.
Some heavy duty pneumatic radial tires have a block-based tread pattern. This block-based tread pattern has a plurality of rectangular blocks formed by a plurality of main grooves extending in a tire circumferential direction and a plurality of sub grooves extending in a tire width direction, whereby a desired wet traction performance and a desired drainage performance are obtained. In the heavy duty pneumatic radial tire, it is also generally assumed that a tire rotation is carried out. Thus, a non-directional tread pattern available for a rotation in both the directions has been a mainstream.
However, in the case of the heavy duty pneumatic radial tire having the block-based tread pattern, a contact pressure loaded to the individual blocks is higher. Therefore, since an amount of block deformation is larger at the time of contacting, heel-and-toe wear is disadvantageously prone to occur. On the other hand, if the block is enlarged in order to suppress the occurrence of heel-and-toe wear, a groove area becomes relatively small. This causes a problem in that the wet traction performance and drainage performance are reduced.